Rolling bearing and spindle device for machine tools

Abstract

A grease-lubricated rolling bearing has an outer ring having an outer ring race in an inner peripheral surface thereof, an inner ring having an inner ring race on an outer peripheral surface thereof, rolling elements rollably provided between the outer ring race and the inner ring race, and a grease supply element for supplying an additional grease in the rolling bearing. The amount of the additional grease to be supplied at a time is predetermined to be from 0.1 to 4% of the volume of space in the bearing.

1. A grease-lubricated rolling bearing comprising:
 an outer ring having an outer ring race in an inner peripheral surface thereof;  
 an inner ring having an inner ring race on an outer peripheral surface thereof;  
 rolling elements rollably provided between the outer ring race and the inner ring race; and  
 a grease supply element for supplying an additional grease in the rolling bearing,  
 wherein the amount of the additional grease to be supplied at a time is predetermined to be from 0.1 to 4% of the volume of space in the bearing,  
 wherein the grease supplying element is a supply hole provided in the outer ring, and  
 wherein the diameter of the supply hole is from 0.1 mm to 5 mm.  
 
   
   
     2. The rolling bearing according to  claim 1 , further comprising:
 a retainer for retaining the rolling elements,  
 wherein the retainer is guided by the outer ring and has a guide surface, and  
 wherein the supply hole opens toward the guide surface of the retainer.  
 
   
   
     3. The rolling bearing according to  claim 1 , wherein the supply hole is radially provided. 
   
   
     4. The rolling bearing according to  claim 1 , wherein the supply hole is axially provided. 
   
   
     5. The rolling bearing according to  claim 1 , wherein the rolling element is a cylindrical roller. 
   
   
     6. The rolling bearing according to  claim 5 ,
 wherein the outer ring has relief portions at both end portions of the outer ring race, and  
 wherein the supply hole is formed to communicate with the relief portion.  
 
   
   
     7. The rolling bearing according to  claim 1 , wherein the rolling element is a ball,
 wherein the ball is disposed between the inner ring race of the inner ring and the outer ring race of the outer ring with a contact angle, and  
 wherein the supply hole provided in the outer ring opens at a position depart from a contact area between the ball and the outer ring race.  
 
   
   
     8. The rolling bearing according to  claim 1 , wherein the rolling bearing is used to support a spindle of a machine tool. 
   
   
     9. The rolling bearing according to  claim 1 , wherein the rolling bearing is used in an operating condition where dmN is not smaller than 1,000,000. 
   
   
     10. A spindle device for a machine tool comprising:
 a rolling bearing for supporting a spindle, the rolling bearing being mounted in a housing, the rolling bearing being grease-lubricated, the rolling bearing comprising:  
 an outer ring having an outer ring race in an inner peripheral surface thereof;  
 an inner ring having an inner ring race in an outer peripheral surface thereof;  
 rolling elements rollably provided between the outer ring race and the inner ring race; and  
 a grease supplying element for supplying an additional grease in the rolling bearing,  
 wherein the amount of the additional grease to be supplied at a time is predetermined to be from 0.1% to 4%,  
 wherein the grease supplying element is a supply hole provided in the outer ring, and  
 wherein the diameter of the supply hole is from 0.1 mm to 5 mm.  
 
   
   
     11. The spindle device according to  claim 10 , wherein the supply hole is radially provided. 
   
   
     12. The spindle device according to  claim 10 , wherein the supply hole is axially provided. 
   
   
     13. A method of lubricating a rolling bearing comprising:
 supplying an initial amount of grease in the rolling bearing;  
 performing a running-in operation of the rolling bearing; and  
 after said running-in operation, supplying additional grease in the rolling bearing;  
 wherein the amount of the additional grease to be supplied is predetermined to be from 0.1 to 4% of the volume of space in the bearing.  
 
   
   
     14. The method according to  claim 13 , wherein the rolling element is a cylindrical roller. 
   
   
     15. The method according to  claim 14 , wherein the initial amount of grease supplied is approximately eight to fifteen percent of the volume of space in the bearing. 
   
   
     16. The method according to  claim 13 , wherein the rolling element is a ball. 
   
   
     17. The method according to  claim 16 , wherein the initial amount of grease supplied is approximately ten to twenty percent of the volume of space in the bearing. 
   
   
     18. The method according to  claim 13 , wherein the additional grease is supplied at a time that is not greater than approximately one-half the lifetime of the grease.